Finite Element Modeling of Selective Laser Melting 316L Stainless Steel Parts for Evaluating the Mechanical Properties

2016 ◽  
Author(s):  
Arman Ahmadi ◽  
Narges Shayesteh Moghaddam ◽  
Mohammad Elahinia ◽  
Haluk E. Karaca ◽  
Reza Mirzaeifar
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Stainless Steel ◽  
Finite Element Model ◽  
Grain Boundaries ◽  
Mechanical Response ◽  
Element Model ◽  
Polycrystalline Materials ◽  
Microstructural Properties ◽  
Laser Melting

Selective laser melting (SLM) is an additive manufacturing technique in which complex parts can be fabricated directly by melting layers of powder from a CAD model. SLM has a wide range of application in biomedicine and other engineering areas and it has a series of advantages over traditional processing techniques. A large number of variables including laser power, scanning speed, scanning line spacing, layer thickness, material based input parameters, etc. have a considerable effect on SLM process materials. The interaction between these parameters is not completely studied. Limited studies on balling effect in SLM, densifications under different processing conditions, and laser re-melting, have been conducted that involved microstructural investigation. Grain boundaries are amongst the most important microstructural properties in polycrystalline materials with a significant effect on the fracture and plastic deformation. In SLM samples, in addition to the grain boundaries, the microstructure has another set of connecting surfaces between the melt pools. In this study, a computational framework is developed to model the mechanical response of SLM processed materials by considering both the grain boundaries and melt pool boundaries in the material. To this end, a 3D finite element model is developed to investigate the effect of various microstructural properties including the grains size, melt pools size, and pool connectivity on the macroscopic mechanical response of the SLM manufactured materials. A conventional microstructural model for studying polycrystalline materials is modified to incorporate the effect of connecting melt pools beside the grain boundaries. In this model, individual melt pools are approximated as overlapped cylinders each containing several grains and grain boundaries, which are modeled to be attached together by the cohesive zone method. This method has been used in modeling adhesives, bonded interfaces, gaskets, and rock fracture. A traction-separation description of the interface is used as the constitutive response of this model. Anisotropic elasticity and crystal plasticity are used as constitutive laws for the material inside the grains. For the experimental verification, stainless steel 316L flat dog bone samples are fabricated by SLM and tested in tension. During fabrication, the power of laser is constant, and the scan speed is changed to study the effect of fabrication parameters on the mechanical properties of the parts and to compare the result with the finite element model.

Integrity Evaluation of Steel Flanges Joined with Metallic Gaskets

2013 ◽  
Vol 554-557 ◽  
pp. 2187-2199
Author(s):  
Ragnar Gjengedal ◽  
Ørjan Fyllingen ◽  
Henrik Sture
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Stainless Steel ◽  
Finite Element Model ◽  
Duplex Stainless Steel ◽  
Element Model ◽  
System Integrity ◽  
Steel Bars ◽  
American Standard ◽  
Manufacturing Methods

System integrity of a flanged connection requires that no leakages occur. Metallic flanges and their joining is of great importance when it comes to avoiding leakages from hydrocarbon lines. The American standard ASTM A182 demands that flanges must be forged to shape, thereby excluding other manufacturing methods. Mechanical properties of duplex stainless steel bars have been examined by doing tensile and charpy tests. A finite element model of a typical ASME-flange assembly was made and was used to calculate stress levels in the flange. The measured mechanical properties of the bar, showed that it is suitable for flange use.

Mechanical response of a panel section with a hexagonally tessellated stiffener grid

2016 ◽  
Vol 231 (8) ◽  
pp. 1402-1414
Author(s):  
M Bouazizi ◽  
T Lazghab ◽  
M Soula
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Mechanical Response ◽  
Element Model ◽  
External Loading ◽  
Original Structure ◽  
Hexagonal Grid ◽  
Aircraft Fuselage ◽  
Stiffened Shells ◽  
Analytical Expressions

Stringers are stiffening members of pressurized aircraft fuselage. They provide support to the fuselage’s skin. A new stringer grid concept is proposed for conventional aircraft fuselage. Optimization is used to find the hexagonal grid that best replaces the original while keeping the same total stringer length. A finite element model is built to analyze the optimal hexagonal grid stiffened structure and compare it with the original orthogonally stiffened structure in terms of eigenfrequencies and static response to external loading. The finite element model is validated through Flugge’s analytical expressions for stiffened shells. Results show that the hexagonal grid stiffened structure yields higher eigenfrequencies with stresses and displacements comparable with that of the original structure.

scholarly journals The Development of Finite Element Model to Investigate the Structural Performance of Reinforced Concrete Hollow Beams

2020 ◽  
Vol 6 (1) ◽  
pp. 171
Author(s):  
Jen Hua Ling ◽  
Lin Li Chan ◽  
Wen Kam Leong ◽  
How Teck Sia
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Reinforced Concrete ◽  
Finite Element Model ◽  
Beam Width ◽  
Element Model ◽  
Reinforced Concrete Beam ◽  
Strength Properties ◽  
Beam Deflection ◽  
Hollow Beam

The self-weight of a reinforced concrete beam contributes to the permanent loads of a structure. This can be reduced by creating a longitudinal void along the beam so that it will not affect the performance of the beam. In addition, this process can reduce the amount of building cost. Therefore, a finite element model was developed in this study with the aid of a computer program, Ansys, to investigate the behavior of the hollow beam. The model was tested for reliability by comparing the predicted results with those obtained from the experiment in terms of the load-displacement responses, mechanical properties, and parametric responses. The result showed that the reliability of the model was questionable. The main cause of the non-reliability was the inaccurate prediction of the beam deflection by the model. The poor prediction of beam deflection led to significant variations of relevant mechanical properties including stiffness, deflection, and ductility. For beam deflection, only 1/3 of the specimens were correctly predicted with a reliability of 36% while the strength properties were discovered to have higher values as observed in the yield and the ultimate strengths with 73% and 64% respectively. However, both the model and experimental results showed the hollow beam was relatively effective when the diameter of the longitudinal void was 1/3 times the beam width and placed at the neutral axis. For the evaluation to improve the reliability, some revision including the properties of the materials, boundary conditions of the beam support, bonding conditions between different materials, and meshing shape and size suppose to be applied to the model. 

scholarly journals Hydrogen Effects on the Burst Properties of Type 304L Stainless Steel Flawed Vessels

2008 ◽  
Author(s):  
Michael J. Morgan ◽  
Monica C. Hall ◽  
Poh-Sang Lam ◽  
W. Dean Thompson
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Finite Element Model ◽  
Element Model ◽  
Burst Pressure ◽  
304L Stainless Steel ◽  
Helium Gas ◽  
Lower Volume ◽  
Hydrogen Deuterium ◽  
Deuterium Gas

The effects of hydrogen and burst media on the burst properties of Type 304L stainless steel vessels were investigated. The purpose of the study was to compare the burst properties of hydrogen-charged stainless steel vessels burst with different media: water, helium gas, and deuterium gas. A second purpose was to provide data to improve an existing finite-element model for predicting burst behavior. Burst tests were conducted on hydrogen-charged and uncharged axially-flawed cylindrical vessels. The results indicate that samples burst pneumatically had lower volume ductility than those tested hydraulically. For pneumatic burst tests, samples burst with deuterium gas had slightly lower ductility than helium gas tests. For uncharged samples, burst pressure was not affected by burst media. For samples pre-charged with hydrogen, deuterium burst pressures were about 80% of the hydraulic or helium burst pressures. Hydrogen-charged samples had lower volume ductility and slightly higher burst pressures than uncharged samples. The results of the tests were used to verify and improve a previously developed predictive finite-element model. The existing finite-element model can qualitatively predict the expected changes in burst properties with hydrogen or tritium service, but a better material property database is required for quantitative predictions.

scholarly journals Numerical analysis of concrete-filled spiral welded stainless steel tubes subjected to compression

2018 ◽  
Author(s):  
Dongxu Li ◽  
Brian Uy ◽  
Farhad Aslani ◽  
Chao Hou
Keyword(s):  
Finite Element ◽  
Stainless Steel ◽  
Finite Element Model ◽  
Mechanical Performance ◽  
Load Capacity ◽  
Element Model ◽  
Experimental Program ◽  
Design Parameters ◽  
Steel Tubes ◽  
Finite Element Software

Spiral welded stainless tubes are produced by helical welding of a continuous strip of stainless steel. Recently, concrete-filled spiral welded stainless steel tubes have found increasing application in the construction industry due to their ease of fabrication and aesthetic appeal. However, an in-depth understanding of the behaviour of this type of structure is still needed due to the lack of proper design guidance and insufficient experimental verification. In this paper, the mechanical performance of concrete-filled spiral welded stainless steel tubes will be numerically investigated with a commercial finite element software package, through which an experimental program can be designed properly. Specifically, the proposed finite element models take into account the effects of material and geometric nonlinearities. Moreover, the initial imperfections of stainless steel tubes and the form of helical welding will be appropriately included. Enhancement of the understanding of the analysis results can be achieved by extending results through a series of parametric studies based on the developed finite element model. Thus, the effects of various design parameters will be further evaluated by using the developed finite element model. Furthermore, for the purposes of wide application of such types of structure, the accuracy of the behaviour prediction in terms of ultimate strength based on current design codes will be studied. The authors herein compared the load capacity between the finite element analysis results and the existing codes of practice.

Fully Coupled Three-Scale Finite Element Model for the Mechanical Response of a New Bio-Inspired Composite

2011 ◽  
Author(s):  
Erick I. Saavedra Flores ◽  
Senthil Murugan ◽  
Michael I. Friswell ◽  
Eduardo A. de Souza Neto
Keyword(s):  
Finite Element ◽  
Magnesium Alloy ◽  
Finite Element Model ◽  
Large Scale ◽  
Mechanical Response ◽  
Volume Fraction ◽  
Element Model ◽  
Crystalline Cellulose ◽  
Gauss Point ◽  
Fully Coupled

This paper proposes a fully coupled three-scale finite element model for the mechanical description of an alumina/magnesium alloy/epoxy composite inspired in the mechanics and architecture of wood cellulose fibres. The constitutive response of the composite (the large scale continuum) is described by means of a representative volume element (RVE, corresponding to the intermediate scale) in which the fibre is represented as a periodic alternation of alumina and magnesium alloy fractions. Furthermore, at a lower scale the overall constitutive behavior of the alumina/magnesium alloy fibre is modelled as a single material defined by a large number of RVEs (the smallest material scale) at the Gauss point (intermediate) level. Numerical material tests show that the choice of the volume fraction of alumina based on those volume fractions of crystalline cellulose found in wood cells results in a maximisation of toughness in the present bio-inspired composite.

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